2101 1.3 Plant Life Cycle

Question 1

Stages in plant growth(5)

Answer 1

1. Seed
2. Juvenility
3. Maturity - adult (reproductive stage)
4. Senescence
5. Death

Question 2

What is a seed?

Answer 2

A seed contains and protects plant embryo

Question 3

What is a Viable seed?

Answer 3

Has potential for germination when conditions are right

Question 4

What is a Quiescent Seed

Answer 4

Is a viable seed that does not germinate as conditions are not right

Question 5

What is a dormant seed

Answer 5

A viable seed
Will not germinate even if conditions are right

[scarification / stratification to break dormancy]

Question 6

What is an Orthodox Seed?

Answer 6

Can be stored a long time

Question 7

What is a Recalcitrant Seed

Answer 7

Lose viability quickly

Question 8

What is the Junvenility Stage
[vegatative]?

Answer 8

Rapid plant growth in face of competition. Energy is put into make new leaves and shoots. No flower or fruits.

Question 9

Differences in growth habits early and later stage (3)

Answer 9

1. Growth Habit - horizontal v vertical growth e.g. Hedera helix
2. Leaf shape - e.g. three lobed leaf v oval adult leaf in Hedera helix
3. Colour and leaf arrangement on stem

Question 10

What is the mature (Adult / reproductive stage)

Answer 10

1. Physiological changes to form flower and fruit
2. Juvenile to adult growth takes place at tip of the plant
3. Trigger by environmental changes e.g. temperature / day length
4. Adult growth linked to storing food at end of growing season for overwintering and the following spring
5. Trees can yale 5-40 yrs to reach this stage which is one reason fruiting wood is grafted onto young root stock

Question 11

What is scenescene

Answer 11

Plant growth and rate of new cell production declines. Less able to regenerate tissues in the face of environmental stress and disease

Question 12

What is Abscission

Answer 12

The process of leaf drop.
Corky layer is formed before the leaf is dropped to reduce water loss

Question 13

Plant Death

Answer 13

At end of season for annuals.
At end of plant life for perennials

Question 14

How to make use of plant lifecycle (4)

Answer 14

1. Easier to root cuttings from Juvenile material
2. Coppicing / pollarding used to make hardwood cuttings of oak, beech and fruit trees
3. Some plants gave different growth habits and leaf shapes between Juvenile and Adult stages.
   e.g. young beech holds onto its leaves - beech hedges do, trees dont
   e.g. cutting back Eucalyptus gunii to maintain Junvenile foliage
4. Some conifirs completely different in form and growth in juvenile stage.
   e.g. take cuttings in juvenile stage may fix the growth form of Cryptomeria japonica